Physical Science

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Physical Science
Chapter 19 Acids Bases
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Solutions and Suspensions
Suspension - the particles are temporarily
suspended in the liquid are large enough to
collectively make the material appear cloudy.
They will settle out after a while. Colloidal
dispersion - very small particles spread
throughout the liquid which are large enough to
reflect light, but not large enough to be seen
individually. It may look either clear or cloudy
in ordinary room light. The particles in a
colloidal dispersion remain dispersed in the
liquid and will not settle out. A solution, on
the other hand, will appear clear even when a
light is shown through it. The particles are
completely dissolved never settle out.
A mixture of flour water
Colloidal dispersion spreads the light out
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Solvents and Solutes

• Solvent the part of the solution that is
  present in the largest amount
• Solute the part of the solution present in the
  least amount

Parts of a Solution
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Types of Solutions

• Solutions can be made from different states of
  matter

Ding-a-ling I would know this if I were you
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Particles in solution

• Solute particles are separated from each other
  and are surrounded by solvent particles.
• a. Water is polar and easily dissolves ionic
  compounds i.e. NaCl
• b. Water can also dissolve many nonpolar
  particles because these particles may have a
  slight polar side of the molecule which allows
  the polar water to be attracted to these
  surfaces.
• c. Remember that most molecular bonds are a
  gradient between pure ionic and pure covalent
  types of bonds.

Because of its polarity, water is the universal
solvent
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Concentration

• Concentrated strong solution more solute
  present
• Dilute weak solution less solute present

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Solubility

• Solubility the amount of solute that will
  dissolve in a solvent at a given temperature.
• Unsaturated Solutions - Generally speaking
• 1. Higher temperatures will allow more of a solid
  to dissolve into a liquid
• 2. Higher temperatures will hold less gas in
  solution than colder temperatures
• Saturated point when no more solute can
  dissolve into the solvent at the given temperature

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Effects of Solutes on the Solvent

• Increased concentrations of solute in a solution
  will lower the freezing point and increase the
  boiling point of the pure solvent

i. Salt spread over icy roads to melt the ice and
turn it into water ii. Salt placed into cooking
water will increase the temperature of the water
before it starts to boil, i.e. decreasing cooking
time of pasta as it cooks in hotter water.
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The Dissociation of water
Water can actually dissolve itself by pulling a
proton (Hydrogen atom w/out its electron) off of
one water molecule When proton can be
transferred from one water molecule to another,
resulting in the formation of one hyroxide ion
(OH-) and one hydronium ion (H3O). It will often
do the reverse, change a hydronium ion an
hydroxide ion back into water. The equation goes
both ways until equilibrium is found.
When equilibrium is reached and Hydronium ions
Hydroxide ions the solution is NEUTRAL
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Water pH

• pH -log H
• At equilibrium, the concentration of H
  (Hydronium) is 10-7
• so we can calculate the pH of water at
  equilibrium as
• pH -(logH) -(log10-7)
• pH- (-7) pH 7
• pH scale goes from 0 to 14

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Properties of Acids

• Properties of Acids compounds that
• Release free Hydrogen ions into solution (H)
• Reacts with metals and carbonates
• Turns blue litmus paper red
• Tastes sour (never taste)
• Are corrosive, eating away

Need-to-Know Acids Hydrochloric
HCl Nitric Acid HNO3 Sulfuric Acid
H2SO4 Carbonic Acid H2CO3
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Properties of Bases

• i. Bases are compounds that
• 1. Release hydroxide ions (OH-) into solution
• ii. Has a bitter taste (never taste any solution
  unless told to do so)
• iii. feels slippery
• iv. Reacts with indicators like litmus by turning
  red litmus blue
• v. has a pH greater than 7.0

Need-to-Know Bases Sodium Hydroxide
NaOH Potassium Hydroxide KOH Calcium Hydroxide
Ca(OH)2 Ammonia NH3
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Acids and Bases in Solution

• Acids in Solution
• Acids are made of a H ion and an Anion (a
  negatively charged ion)
• In water, acids dissociate (breakdown) into H
  and anions
• 1. HCl ? H Cl-
• Bases in solution
• Most bases release hydroxides ions into the water
• 1. NaOH ? Na OH-
• 2. NH3 H2O ? NH4 OH-

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Acid / Base Reactions

• When Acids and Bases are combined a
  Neutralization reaction produces water and a salt
• 1. Hydrochloric Acid and Sodium Hydroxide yields
  water and Sodium Chloride
• a. HCl NaOH ? H2O NaCl
• B. H Cl- Na OH- ? H2O NaCl
• 2. Salt is an ionic compound formed from an acid
  / base reaction (neutralization)